This invention relates to an improved intubation device for use in assisting the breathing of a patient and in administering anaesthetics to a patient, for example during a surgical procedure.
To prevent asphyxiation it is essential to maintain a patent airway to the larynx but it is also essential to prevent penetration of blood and other secretions to the lungs. For purposes of maxillary, facial, oral, dental, nasal, ear and throat surgery it has therefore been common to use an endotracheal tube, which has an inflated cuff which seals the trachea below the vocal cords. However an endotracheal tube cannot be used without first inducing neuromuscular paralysis in the patient, as otherwise touching the vocal cords will induce a reflex spasm which will close the larynx.
International Patent Application publication No. WO 95/33506 and the British patent publications to which it refers disclose a laryngeal mask which, because it is located around the epiglottis and outside the laryngeal inlet, may be used without neuromuscular paralysis. However this mask is a relatively large object and because of its shape presents problems of location which give rise to dangers of injury to the patient. International Patent Application publication No. WO 95/06492 discloses an alternative to the laryngeal mask, the so-called COPA, which is located higher in the throat and which seals it by forcing forward the tongue and closing the naso-pharynx by lifting the soft palate. Both of these devices must be introduced orally, the laryngeal mask because it is too large to be introduced through the nose and the COPA not only for this reason but because it must close the back of the nose. Therefore both are unsuitable when access to the mouth is required and the COPA device is particularly unsuitable for operations on the back of the mouth or the throat, such as tonsilectomy, because its cuff projects into the oral cavity obscuring both the red tonsils and the uvula.
The principal object of the present invention is to improve upon prior art devices by providing a cuffed tube which although small enough to be introduced through the nose will effectively seal the throat above the epiglottis, at the same time providing access to the back of the mouth.
In accordance with one aspect of the present invention, there is provided an intubation device comprising an airway tube including a proximal end, a distal end and a wall where the airway tube is dimensioned for nasal insertion to introduce the tube into the throat of a patient. The intubation device also includes an inflatable cuff surrounding the distal end of the airway tube where the inflatable cuff has a generally flat distal surface, an anterior surface, and a generally flat postenor surface generally parallel with the airway tube. The generally flat distal surface forms an acute angle with the posterior surface and forms an obtuse angle with the anterior surface. The distal end of the airway tube is recessed into the distal surface of the inflatable cuff and the distal surface forms a distal protrusion beyond the airway tube. The inflatable cuff, when uninflated, is dimensioned to permit nasal insertion of the device into the throat of a patient and, when inflated is dimensioned and shaped to enter the vallecula and seat over an upper region only of the ellipical epiglottis and to seal the piriform fossae on either side thereof. The distal surface is adapted to seal against the posterior pharyngeal wall. The cuff reduces in cross-sectional area away from the distal protrusion such that when inflated the cuff will span the oro-pharynx in a region behind the palatopharyngeal folds below the soft palate and above the laryngeal inlet substantially without intrusion into the oral cavity.
It will of course be understood that the fact that the device of the invention can be introduced nasally in no way prevents its insertion orally if that is the preferred option in general airway management.
References to a xe2x80x9ccuffxe2x80x9d are used herein to denote both a balloon surrounding the tube and a tubular membrane sealed at opposite ends to the tube periphery.
When inflated the cuff is preferably a generally polyhedral body all the corners of which are rounded.
Preferably the plane of said annular protrusion forms an angle of approximately 45xc2x0 with respect said longest side in the inflated condition of the cuff.
In a preferred embodiment the cuff when inflated has generally the shape of a frustum of a four-sided pyramid of which said longest side is the base, the plane of a proximal surface of the cuff being generally at right angles to the plane of the base.
Preferably the cuff is provided both with a one-way inflation valve and with a pressure-relief valve, the latter being preset to prevent pressure within the cuff rising above a predetermined value. The pressure-relief valve may be adjustable to vary the predetermined pressure within the cuff which will open the pressure-relief valve. The pressure-relief valve is desirable to prevent over expansion of the cuff, with consequent harm to the patient, which may occur during anaesthesia if anaesthetic gases migrate into the cuff through its membrane material.
The said valves are preferably in a common housing which is associated with a pilot balloon, the interior of the pilot balloon communicating with the interior of the cuff via an auxiliary line at least part of the length of which is within the wall of the tube.
When the device is to be introduced orally it may further comprise a combined bite-block and connector element insertable in a proximal end of the tube and an apertured mouth surround element which extends from opposite sides of the connector element, the aperture or apertures of the mouth surround element permitting insertion into the mouth of suction equipment alongside said tube when the mouth surround element extends over the mouth of a patient.
The mouth surround element may have an elliptical aperture in the centre of which is a circular component adapted to surround the combined bite-block and connector element.
Opposite ends of the mouth surround element are preferably engageable by opposite ends of an elastic head band, the connection between each end of the band and the mouth surround being by means of components which can be snapped off to permit quick removal of the mouth surround from the face.